/*
 * The MIT License
 *
 * Copyright (c) 2007 MIT 6.270 Robotics Competition
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 *
 */

#include "hal/io.h"
#include "hal/adc.h"
#include "kern/lock.h"

#define PRESCALER	0x7

struct lock adc_lock;

void
adc_init (void) {
	init_lock(&adc_lock, "adc lock");
}

int8_t
adc_get_sample (adc_ref ref, adc_input config, uint16_t * val)
{
	acquire(&adc_lock);

	ADMUX = (ref << 7) | _BV(REFS0) | /*_BV(ADLAR) |*/ config;
	ADCSRA = _BV(ADEN) | _BV(ADSC) | _BV(ADIF) | PRESCALER;

	while (!(ADCSRA & _BV(ADIF)));
	ADCSRA |= _BV(ADIF);

	*val = ADCL;
	*val |= (ADCH << 8);

	release(&adc_lock);
	return ADC_SUCCESS;
}
